Section 1905A

MODIFICATIONS TO ACI 318

1905 A .1 General. The text of ACI 318 shall be modified as indicated in Sections 1905 A .1.1 through 1905A.1.17.

1905A.1.1 ACI 318, Section 4.12.2.2. Modify ACI 318, Section 4.12.2.2 by adding the following:

Where prestressed concrete elements are restrained from movement, an analysis of the stresses in the pre- stressed elements and loads in the adjoining structural sys- tem induced by the above-described effects shall be made in accordance with PCI Design Handbook.

1905A.1.2 ACI 318, Section 4.12.2.3. Modify ACI 318, Section 4.12.2.3 by adding the following:

For prestressed concrete members with recessed or dapped ends, an analysis of the connections shall be made in accordance with procedures given in PCI Design Hand- book. 1905A.1.3 ACI 318, Section 9.6.1.3. Modify ACI 318, Sec- tion 9.6.1.3 by adding the following:

This section shall not be used for members that resist seismic loads, except for either of the following conditions:

1. Foundation members for one-story wood-frame or one-story light steel buildings.

2. Foundation members designed for seismic load combinations including the overstrength factor.

[OSHPD 1 & 4] The A s provided shall not be less than that required by 1.2 times the cracking load based upon f r defined in Section 19.2.3.

1905A.1.4 ACI 318, Section 11.2.4.1. Replace ACI 318, Section 11.2.4.1 as follows:

11.2.4.1 – Walls shall be anchored to intersecting elements such as floors or roofs; or to columns, pilas- ters, buttresses, of intersecting walls and footings with reinforcement at least equivalent to No. 4 bars at 12 inches (305 mm) on center for each layer of reinforcement.

1905A.1.5 ACI 318, Section 11.7. Add Section 11.7.6 to ACI 318.1 as follows:

11.7.6 – Reinforcement. Perimeters of precast walls shall be reinforced continuously with a minimum of one

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CONCRETE

No. 5 bar in diaphragms having a single layer of rein- forcement in both directions shall be provided around openings larger than 12 inches in any dimension in addition to the minimum reinforcement required by Section 12.6.

1905 A .1.8 ACI 318, Section 17.10 . Modify ACI 318 Sections 17.10.5.2, 17.10.5.3(d) and 17.10.6.2 to read as follows:

- 17.10.5.2 – _Where_ the tensile component of the

strength-level earthquake-induced force applied to anchors exceeds 20 percent of the total factored anchor tensile force associated with the same load combination, anchors and their attachments shall be designed in accordance with 17.10.5.3. The anchor design tensile strength shall be determined in accordance with 17.10.5.4.

Exception: Anchors designed to resist wall out- of-plane forces with design strengths equal to or greater than the force determined in accordance with ASCE 7, Equation 12.11-1 or 12.14-10, and Section 1604A.8.2 of this code shall be deemed to satisfy Section 17.10.5.3(d).

- 17.10.5.3(d) – _The_ anchor or group _of anchors_ shall

be designed for the maximum tension obtained from design load combinations that include E, with E increased by Ω0. The anchor design tensile strength shall be calculated in accordance with 17.10.5.4.

- 17.10.6.2 – _Where_ the shear component of the

strength-level earthquake force applied to anchors exceeds 20 percent of the total factored anchor shear force associated with the same load combination, anchors and their attachments shall be designed in accordance with 17.10.6.3. The anchor design shear strength for resisting earthquake forces shall be determined in accordance with 17.7.

Exceptions:

1. For the calculation of the in-plane shear strength of anchor bolts attaching wood sill plates of bearing or nonbearing walls of light-frame wood structures to foundations or foundation stem walls, the in-plane shear strength in accordance with 17.7.2 and 17.7.3 need not be computed and 17.10.6.3 shall be deemed to be satisfied provided all of the following are met:

1.1. The allowable in-plane shear strength of the anchor is determined in accordance with ANSI/AWC NDS Table 12E for lateral design values parallel to grain. 1.2. The maximum anchor nominal diameter is ⁵ /8 inch (16 mm). 1.3. Anchor bolts are embedded into concrete a minimum of 7 inches (178 mm). 1.4. Anchor bolts are located a minimum of 1 ³ /4 inches (45 mm) from the edge

of the concrete parallel to the length of the wood sill plate. 1.5. Anchor bolts are located a minimum of 15 anchor diameters from the edge of the concrete perpendicular to the length of the wood sill plate. 1.6. The sill plate is 2-inch (51 mm) or 3-inch (76 mm) nominal thickness.

2. For the calculation of the in-plane shear strength of anchor bolts attaching cold- formed steel track of bearing or nonbear- ing walls of light-frame construction to foundations or foundation stem walls, the in-plane shear strength in accordance with 17.7.2 and 17.7.3 need not be computed and 17.10.6.3 shall be deemed to be satis- fied provided all of the following are met:

2.1. The maximum anchor nominal diameter is ⁵ /8 inch (16 mm). 2.2. Anchors are embedded into concrete a minimum of 7 inches (178 mm). 2.3. Anchors are located a minimum of 1 ³ /4 inches (45 mm) from the edge of the concrete parallel to the length of the track. 2.4. Anchors are located a minimum of 15 anchor diameters from the edge of the concrete perpendicular to the length of the track. 2.5. The track is 33 to 68 mil (0.84 mm to 1.73 mm) designation thickness.

Allowable in-plane shear strength of exempt anchors, parallel to the edge of concrete, shall be permitted to be determined in accordance with AISI S100 Section J3.3.1.

3. In light-frame construction bearing or non- bearing walls, shear strength of concrete anchors less than or equal to 1 inch [25 mm] in diameter attaching sill plate or track to foundation or foundation stem wall need not satisfy 17.10.6.3(a) through (c) when the design strength of the anchors is determined in accordance with 17.7.2.1(c).

1905A.1.9 ACI 318, Section 18.5. [DSA-SS] Modify ACI 318, Section 18.5, by replacing Section 18.5.2.1, adding new Section 18.5.2.2 and renumbering existing Sections 18.5.2.2 and 18.5.2.3 to become 18.5.2.3 and 18.5.2.4, respectively:

18.5.2.1 – In connections between wall panels, yielding shall be restricted to steel elements or reinforcement. In connections between wall panels and the foundation, they shall be designed per Section 1617A.1.16. 18.5.2.2 – Connections that are designed to yield shall be capable of maintaining 80 percent of their design strength at deformation induced by the design displace- ment or shall use type 2 mechanical splices.

19A-6 2022 CALIFORNIA BUILDING CODE

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1. For sections classified as transition, it shall be permitted to use φ corresponding to compression-controlled sections. 2. ε t * is the greater of net tensile strain calculated for P n = 0.1A g f ′ c and ε t y +

0.003 . 3. For sections with factored axial compression force P u ≥ 0.1A g f ′ c , φ shall be calculated using equation (c) or (d) for sections classified as transition, as applicable.

1905A.1.14 ACI 318, Section 24.2.1. Add Section 24.2.1.1 to ACI 318 as follows:

24.2.1.1 – Span to depth ratio. Prestressed beam and slab span to depth ratios for continuous prestressed concrete members shall not exceed the following, except when cal- culations of deflections and vibration effects prove that greater values may be used without adverse effects:

Beams...................................... 30

One-way slabs......................... 40

Two-way floor slabs................ 40

Two-way roof slabs................. 44

These ratios should be decreased for special condi- tions such as heavy loads and simple spans.

Maximum deflection criteria shall be in accordance with ACI 318 Section 24.2.2.

1905A.1.15 ACI 318, Section 25.2.10. Replace ACI 318 Section 25.2.10 by the following:

25.2.10 For ties and hoops in columns to be placed with shotcrete, minimum clear spacing shall be 3 in. Shot- crete shall not be applied to spirally tied columns.

1905A.1.16 ACI 318, Section 26.5.2. Modify ACI 318 Section 26.5.2.1 by replacing items (l), (m) and (n) and adding item (q) as follows:

(l) Shotcrete surfaces intended to receive subsequent shotcrete placement following an interruption of 30 minutes or more shall be roughened to a full amplitude of approximately ¹ /4 in. before the shotcrete has reached final set. The film of laitance which forms on the surface of the shotcrete shall be removed within approximately 2 hours after application by brushing with a stiff broom. If this film is not removed within 2 hours, it shall be removed by thorough wire brushing or a mechani- cal method acceptable to the enforcement agency.

CONCRETE

1905A.1.13 ACI 318, Table 21.2.2. Replace Table 21.2.2 as follows:

TABLE 21.2.2 STRENGTH REDUCTION FACTOR φ FOR MOMENT, AXIAL FORCE, OR COMBINED MOMENT AND AXIAL FORCE

18.5.2.3 - Elements of the connection that are not designed to yield shall develop at least 1.5 Sy .

18.5.2.4 - In structures assigned to SDC D, E or F, wall piers shall be designed in accordance with 18.10.8 or 18.14 in ACI 318.

1905A.1.10 ACI 318, Section 18.10.6.5. Modify ACI 318, Section 18.10.6.5 by adding the following:

(c) Where boundary members are not required by ACI 318 Section 18.10.6.2 or 18.10.6.3 minimum reinforce- ment parallel to the edges of all structural walls and the boundaries of all openings shall consist of twice the cross-sectional area of the minimum shear reinforce- ment required per lineal foot of wall. Horizontal extent of boundary element shall be in accordance with ACI 318 Section 18.10.6.4 (a), (b) and (c).

1905A.1.11 ACI 318, Section 18.12.6. Add Section 18.12.6.2 to ACI 318 as follows:

18.12.6.2 – Collector and boundary elements in top- ping slabs placed over precast floor and roof elements shall not be less than 3 inches (76 mm) or 6 d b thick, where d b is the diameter of the largest reinforcement in the topping slab.

1905A.1.12 ACI 318, Section 19.2.1.1 and Table 19.2.1.1. Modify ACI 318, Section 19.2.1.1 and Table 19.2.1.1 as follows:

19.2.1.1 The value of f´c shall be in be in accordance with (a) through (e) :

(a) Limits for f´c in Table 19.2.1.1. Limits apply to

both normalweight and lightweight concrete.

(b) Durability requirements in Table 19.3.2.1.

(c) Structural strength requirements.

(d) f´c for lightweight concrete in special moment

frames and special structural walls, and their foundations, shall not exceed 5000 psi, unless demonstrated by experimental evidence that members made with lightweight concrete provide strength and toughness equal to or exceeding those of comparable members made with normalweight concrete of the same strength.

(e) Reinforced normal weight concrete with speci-

fied compressive strength higher than 8,000 psi

Copyright © 2022 by, or licensed to, International Code Council, Inc. (ALL RIGHTS RESERVED); licensed to California Building Standards Commission pursuant to License Agreement. No further reproductions is authorized. Any unauthorized reproduction or distribution is a violation of the federal copyright act and the license agreement, and subject to civil and criminal penalties thereunder.

CONCRETE

(m) Before placing additional material onto hardened

shotcrete, laitance shall be removed, joints shall be cleaned, and the surface shall be dampened. Con- struction joints over 8 hours old shall be thor- oughly cleaned with air and water prior to receiving shotcrete. (n) In-place fresh concrete that exhibits sags, sloughs,

segregation, honeycombing, sand pockets, or other obvious defects shall be removed and replaced. Shotcrete above sags and sloughs shall be removed and replaced while still plastic. (q) Surface preparation: Concrete or masonry to

receive shotcrete shall have the entire surface thoroughly cleaned and roughened by a mechani- cal method acceptable to the enforcement agency, and just prior to receiving shotcrete shall be thor- oughly cleaned of all debris, dirt and dust. Con- crete and masonry shall be brought to a saturated surface-dry (SSD) condition before shotcrete is deposited. 1905A.1.17 ACI 318, Section 26.12.2.1(a). Replace ACI 318 Section 26.12.2.1(a) by the following:

detrimental to the intended occupancy of the building.

4. For driveways, walks, patios and other flatwork that will not be enclosed at a later date.

5. Where approved based on local site conditions.